<template>
  <div class="score-case">
    <div class="table">
      <table>
        <thead>
          <tr>
            <th>编号</th>
            <th>科目</th>
            <th>成绩</th>
            <th>考试时间</th>
            <th>操作</th>
          </tr>
        </thead>

        <tbody v-if="list.length">
          <tr v-for="(item, index) in list" :key="item.id">
            <td>{{index +1}}</td>
            <td>{{item.subject}}</td>
            <td :class="{red: item.score < 60}">{{item.score}}</td>
            <td>{{formatDate(item.date)}}</td>
            <td><a href="#" @click.prevent="del(item.id) ">删除</a></td>
          </tr>
        </tbody>

        <tbody v-else>
          <tr>
            <td colspan="5">
              <span class="none">暂无数据</span>
            </td>
          </tr>
        </tbody>

        <tfoot>
          <tr>
            <td colspan="5">
              <span>总分：{{ sumScore}}</span>
              <span style="margin-left:50px">平均分：{{avgScore}}</span>
            </td>
          </tr>
        </tfoot>
      </table>
    </div>
    <div class="form">
      <div class="form-item">
        <div class="label">科目：</div>
        <div class="input">
          <input v-model.trim="subject" type="text" placeholder="请输入科目" />
        </div>
      </div>
      <div class="form-item">
        <div class="label">分数：</div>
        <div class="input">
          <input v-model.number="score" type="text" placeholder="请输入分数" />
        </div>
      </div>
      <div class="form-item">
        <div class="label"></div>
        <div class="input">
          <button class="submit" @click="submit">添加</button>
        </div>
      </div>
    </div>
  </div>
</template>

<script>
// 1. 利用v-for进行基本渲染
// 2. 注册点击事件, 阻止默认行为
// 3. 传递id找到要删除谁 
// 4. 当数据没有了,显示个默认的结构
// 5. 利用v-model获取科目和分数的数据
// 6. 给按钮他添加点击事件 点击的时候把科目和分数加到list数组里
// 7. 加完之后把input框清空
// 8. 利用moment格式化时间  定义一个函数去做
// 9. 利用计算属性 渲染总分和平均分
// 10. list变化,把list转成JSON字符串存到localStorage中
// 11. data里默认将list变量从localStorage中取值, 取不到给个空数组
import moment from 'moment'
export default {
  name: 'ScoreCase',
  data () {
    return {
      // JSON.parse() 将JSON字符串转换成原有数据 (数据1 || 数据2) 语法 前面如果为真返回前面的数据,否则返回后面的
      list: JSON.parse(localStorage.getItem('list')) || [
        {id: 15, subject: '语文', score: 89, date: new Date('2022/06/07 10:00:00')},
        {id: 27, subject: '数学', score: 100, date: new Date('2022/06/07 15:00:00')},
        {id: 32, subject: '英语', score: 56, date: new Date('2022/06/08 10:00:00')},
        {id: 41, subject: '物理', score: 76, date: new Date('2022/06/08 10:00:00')}
      ],
      subject: '',
      score: '',
      num:0
    }
  },
  methods: {
    del (id) {
      console.log(id);
      // filter方法 筛选出符合条件的新数组
      //删除某一id 的项 => 过滤出所有不是该id的项
      this.list = this.list.filter(item => item.id !== id)
    },
     submit() {
      if (this.subject && (this.score >= 0 && this.score !== '' && this.score <= 100)) {
        this.list.push({
          id: + new Date(),
          subject: this.subject,
          score: this.score,
          date: new Date()
        })
        this.subject = ''
        this.score = ''
      } else {
        alert('你不要瞎搞')
      }
     },
     formatDate(date) {
      return moment(date).format('YYYY/MM/DD HH:mm:ss')
     },
     // 会无限循环,不要这么玩
     test() {
      this.num++
      return this.num
     }
  },
  computed: {
    // 总分  求和
    sumScore() {
      // 利用reduce 求和
      return this.list.reduce((sum,item) => sum + item.score , 0)
    },
    avgScore() {
      // 总分/个数
      return this.list.length ? (this.sumScore/this.list.length).toFixed(2) : 0
    }
  },
  watch: {
    list: {
      deep: true,
      handler(val) {
        console.log(JSON.stringify(val));
        // JSON.stringify() 转化成json字符串
        // localStorage.setItem('存储的key值', 存储的value) 设置本地存储
        localStorage.setItem('list', JSON.stringify(val))

      }
    }
  }
};
</script>

<style lang="less">
.score-case {
  width: 1000px;
  margin: 50px auto;
  display: flex;
  .table {
    flex: 4;
    table {
      width: 100%;
      border-spacing: 0;
      border-top: 1px solid #ccc;
      border-left: 1px solid #ccc;
      th {
        background: #f5f5f5;
      }
      tr:hover td {
        background: #f5f5f5;
      }
      td,
      th {
        border-bottom: 1px solid #ccc;
        border-right: 1px solid #ccc;
        text-align: center;
        padding: 10px;
        &.red {
          color: red;
        }
      }
    }
    .none {
      height: 100px;
      line-height: 100px;
      color: #999;
    }
  }
  .form {
    flex: 1;
    padding: 20px;
    .form-item {
      display: flex;
      margin-bottom: 20px;
      align-items: center;
    }
    .form-item .label {
      width: 60px;
      text-align: right;
      font-size: 14px;
    }
    .form-item .input {
      flex: 1;
    }
    .form-item input,
    .form-item select {
      appearance: none;
      outline: none;
      border: 1px solid #ccc;
      width: 200px;
      height: 40px;
      box-sizing: border-box;
      padding: 10px;
      color: #666;
    }
    .form-item input::placeholder {
      color: #666;
    }
    .form-item .cancel,
    .form-item .submit {
      appearance: none;
      outline: none;
      border: 1px solid #ccc;
      border-radius: 4px;
      padding: 4px 10px;
      margin-right: 10px;
      font-size: 12px;
      background: #ccc;
    }
    .form-item .submit {
      border-color: #069;
      background: #069;
      color: #fff;
    }
  }
}
</style>